Swine dysentery is a severe debilitating disease of pigs estimated to cause over 70 million dollars annual loss in the United States. The economic loss is due to death of pigs, decreased growth rate of pigs, and poor feed conversion efficiency by pigs having swine dysentery, as well as expenses incurred by chemotherapy. Harris and Glock report that morbidity of swine dysentery in field cases may approach 90 percent and mortality may be as high as 30 percent. See Diseases of Swine, 5th Edition, p. 432 et. seq. (Iowa State University Press, 1981).
The primary causative organism of swine dysentery is Treponema hyodysenteriae which induces lesion formation on the large intestine. Infected pigs generally suffer from diarrhea although the severity may vary. The ultimate cause of death is usually associated with dehydration, acidosis, and hyperkalemia due to the diarrhea.
Various antimicrobials and antibiotics are currently used in treating swine dysentery, although strains of T. hyodysenteriae resistant to all of the presently approved therapeutics have been reported. Hence, it would be desirable to provide an effective, low dosage therapeutic which would be used in treating this economically devasting disease.